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'LORADO  SCIENTIFIC  SOCIETY. 


'ORT  OF  THE   EXECUTIVE   COMMITTEE    OF   THE 
COLORADO  SCIENTIFIC  SOCIETY  FOR 
THE  YEAR  1911. 

tEPORT  OF  THE    TREASURER   OF  THE    COLORADO 

SCIENTIFIC  SOCIETY  FOR  THE  YEAR  ENDING 

DECEMBER  16TH,  1911. 


THE  WATER  SUPPLY  OF  COLORADO. 

| 

By  CHARLES  W.  COMSTOCK. 

A  CRITICAL  DISCUSSION  OF  THE  PRINCIPLES  OF 
THE  RICHARDS  PULSATOR  CLASSIFIER 


By  LEWIS  B.  SKINNER. 


DENVER, 

PUBLISHED  BY  THE  SOCIETY 
APRIL,  1912. 


BANCROFT 
UBHAftY 


• 


' 

L^     <sP      CrrPo-*  ' 


REPORT  OF  THE  EXECUTIVE  COMMITTEE   OF  THE 

COLORADO  SCIENTIFIC  SOCIETY  FOR 

THE  YEAR  1911. 

Denver,  Colorado,  December  16th,  1911. 
By  the  Secretary. 

During  the  past  year  the  proceedings  of  your  Society 
show  that  nine  regular  meetings  were  held,  with  an  average 
attendance  of  26-2/3,  and  that  nine  papers  were  presented 
and  read.  The  papers  read,  with  their  titles  and  authors, 
were  as  follows : 

"A  Discussion  of  Rock  Streams  with  Special  Reference 
to  the  Rock  Streams  of  Veta  Peak,  Colorado,"  by  Dr.  Horace 
B.  Patton. 

"Description  of  a  Tin  Deposit  in  Texas,"  by  Dr.  Regis 
Chauvenet. 

"Genesis  of  Ore  Deposits,"  by  Mr.  George  J.  Bancroft. 

"A  Recent  Trip  to  Honduras,"  by  Mr.  Rensselaer  H.  Toll. 

"Asbestos  Deposits  of  Casper  Mountain,  Wyoming,"  by 
Mr.  Henry  C.  Beeler. 

"The  105th  Meridian  and  the  Mile  High  Level,  in  Denver," 
by  Dr.  Herbert  A.  Howe. 

"Eskimo  Dogs,  Their  Origin,  and  an  Example  of  Rever- 
sion," by  Mr.  J.  D.  Figgins. 

"The  Occurrence  and  Origin  of  Nitrates  in  Colorado  Soils ; 
Some  of  Their  Effects  and  What  They  Suggest,"  by  Dr.  Wil- 
liam P.  Headden. 

"Screenless  Sizer,"  by  Mr.  James  M.  McClave. 

There  were  nine  papers  published  this  year,  the  same 
number  having  been  published  last  year. 

The  lowest  attendance  at  any  meeting  was  14  in  Septem- 
ber, while  the  highest  was  37  in  April.  The  average  atten- 
dance for  the  nine  meetings  was  26-2/3.  In  1910  the  lowest 
attendance  at  any  meeting  was  23  in  December,  and  the  high- 
est was  108  in  April,  the  average  being  40.3. 


. 


ii  REPORT    OF    THE    EXECUTIVE    COMMITTEE 

During  the  year  24  members  have  been  elected.  The  loss 
has  been  21;  6  by  death  and  15  by  resignation,  leaving  a  net 
gain  of  3.  Those  lost  by  death  were  as  follows :  Mr.  Robert 
Forrester,  who  died  December  20th,  1910;  Mr.  John  E.  Chap- 
son,  who  died  January  20th,  1911;  Mr.  Samuel  F.  Emmons, 
who  died  March  28th,  1911;  Mr.  James  B.  Grant,  who  died 
November  1st,  1911;  Mr.  Charles  B.  Kountze,  who  died  No- 
vember 17th,  1911;  and  Judge  Carlton  M.  Bliss,  who  died 
November  27th,  1911. 

Of  the  present  total  membership  of  252,  154  reside  in 
Denver;  46  outside  of  Denver,  in  Colorado;  41  outside  of 
Colorado,  in  the  United  States,  and  11  in  foreign  lands.  The 
roll  consists  of  4  life  members,  9  honorary  fellows,  13  fellows, 
173  members,  38  associates,  and  15  who  have  not  as  yet  been 
graded. 

The  Executive  Committee  held  5  regular  meetings,  with 
an  average  attendance  of  6-1/5,  besides  several  informal  meet- 
ings. 

There  have  been  6  exchanges  added  during  the  past  year, 
viz. :  American  Brass  Founders'  Association,  Australian  Min- 
ing and  Engineering  Review,  Colorado  School  of  Mines,  Eco- 
nomic Geology,  Carnegie  Library  of  Pittsburgh,  and  the  Pat- 
ent Office  Library  of  London. 

The  number  of  visitors  to  the  museum  and  library  during 
the  past  year  was  1,321,  the  number  last  year  being  1,336. 

Books  added  to  the  library  during  1911  were  as  follows: 

By  Purchase  — 

American  Society  of  Mechanical  Engineers,  Volumes  29, 
30  and  31. 

By  Gift— 

Annual  Report  of  the  Smithsonian  Institution  for  1909. 

Annual  Report  of  the  United  States  National  Museum  for 
1910. 

Twenty-seventh  Annual  Report  of  the  Bureau  of  Ameri- 
can Ethnology  for  1905  and  1906. 


REPORT    OF    THE    EXECUTIVE    COMMITTEE  iii 

Twenty-fourth  Annual  Report  of  the  Interstate  Commerce 
Commission  for  1910. 

Biennial  Report  of  the  State  Historical  and  Natural  His- 
tory Society  of  Colorado  for  1909  and  1910. 

Bureau  of  American  Ethnology,  Bulletin  Number  40, 
Part  1 ;  also  Bulletin  Numbers  43,  44,  50  and  51. 

Colorado  Geological  Survey  Bulletin,  Numbers  1  and  2, 
presented  by  Mr.  W.  F.  R.  Mills. 

Congressional  Records — Index  to  Volume  41,  Parts  1-5; 
also  Volume  42,  Parts  1,  3,  7  and  8. 

Geological  Survey  of  Ohio,  Fourth  Series,  Bulletin  Num- 
bers 2,  12  and  13. 

Geological  Survey  of  Iowa,  Volume  20,  and  Annual  Report 
for  1909. 

Library  of  Congress  Report  for  1910. 

Mineral  Resources  for  1909,  Parts  1  and  2. 

Oklahoma  Geological  Survey,  Bulletin  Numbers  2,  5 
and  8. 

Proceedings  of  the  Iowa  Academy  of  Science  for  1910, 
Volume  17. 

Proceedings  of  the  United  States  National  Museum,  Vol- 
umes 30,  39  and  40. 

Records  of  the  Geological  Survey  of  New  South  Wales, 
Volume  9,  Part  1. 

The  Mineralogy  of  Pennsylvania,  presented  by  Mr.  John 
Eyerman. 

The  Railway  Library  for  1910. 

Wisconsin  Geological  and  Natural  History  Survey,  Bul- 
letin Numbers  21  and  22 ;  also  Scientific  Series  Num- 
bers 6  and  7. 

During  the  past  year  the  Society  has  been  organized  into 
5  sections,  viz.: 

1 — Technical  Chemistry  and  Metallurgy.  Secretary,  Mr. 
H.  0.  Bosworth. 

2 — Economic  Geology  and  Mining  Engineering.  Secre- 
tary, Mr.  S.  A.  lonides. 


iV  REPORT    OF    THE    EXECUTIVE    COMMITTEE 

3 — Mechanical  and  Electrical  Engineering.  Secretary, 
Mr.  H.  S.  Sands. 

4 — Irrigation  and  Civil  Engineering.  Secretary,  Mr.  F. 
W.  Bosco. 

5 — Pure  Science.     Secretary,  Mr.  G.  M.  Butler. 

These  Sections  have  held  meetings  during  the  year  as 
follows : 

April  8th — Section  1  held  its  first  regular  meeting,  at 
which  Mr.  Lewis  B.  Skinner  presided.  He  gave  the  address 
of  the  evening  on  "The  Practical  Versus  the  Theoretical  Man/' 

April  21st — Section  2  held  its  first  regular  meeting,  Mr. 
S.  A.  lonides  presiding.  Mr.  George  J.  Bancroft  read  a  paper 
on  "The  Superficial  Appearance  and  Alteration  of  Ore  De- 
posits.'* 

September  9th — Section  1  held  its  second  regular  meet- 
ing, Prof.  Herman  Fleck  acting  as  chairman.  The  chair  read 
a  paper  which  had  been  prepared  for  this  meeting  by  Mr. 
F.  L.  Clerc  on  "The  Utilization  of  the  Zinc  Carbonates  and 
Silicates  of  Leadville,  Colorado." 

November  18th — Section  1  held  its  third  regular  meeting, 
Mr.  Howard  C.  Parmelee  presiding.  Dr.  Bain  read  a  paper  en- 
titled "Methods  of  Ore  Treatment." 

November  25th — Section  5  held  its  first  regular  meeting, 
Mr.  George  E.  Collins  acting  as  chairman.  The  following 
papers  were  read:  "Recent  Developments  in  Physics,"  by 
Prof.  L.  F.  Miller;  "Recent  Developments  in  Chemistry,"  by 
Dr.  J.  B.  Ekeley,  and  "Recent  Developments  in  Geology,"  by 
Prof.  G.  M.  Butler. 

In  addition  to  these,  under  the  auspices  of  this  Society 
and  the  State  School  of  Mines,  meetings  have  been  held  at 
Idaho  Springs,  Leadville,  Telluride  and  Ouray,  for  the  purpose 
of  stimulating  the  mining  industry  of  the  state  by  "Practical 
Talks"  by  well  known  scientific  engineers  to  the  miners, 
mine  and  mill  operators  of  these  towns.  These  meetings  have 
met  with  much  encouragement  from  the  mining  communities 


REPORT    OF    THE    EXECUTIVE    COMMITTEE  v 

and  the  expectation  of  good  results  along  the  line  of  more  eco- 
nomic management  of  mines  and  mills  is  well  warranted. 

With  the.  view  of  broadening  the  usefulness  of  this  So- 
ciety and  obtaining  a  fuller  measure  of  benefit  of  the  scien- 
tific labor  of  the  community,  in  the  spring  of  this  year,  sec- 
tions were  organized.  It  was  considered  that  these  sections 
would  allow  for  specialization  under  one  organization,  which 
would  result  in  economy  in  many  ways;  affording  a  common 
meeting  place  for  members,  devoting  special  attention  to  dif- 
ferent branches  of  scientific  investigation,  a  better  frater- 
nizing of  these  specialists,  a  more  beneficial  interchange  of 
ideas  and  a  greater  promotion  of  useful  knowledge.  These 
sections  are  just  now  getting  into  working  order,  and  there 
is  every  reason  to  expect  the  most  satisfactory  results  from  the 
experiment. 

On  account  of  threats  of  increased  rental  at  our  former 
headquarters  at  1510  Court  Place,  it  was  considered  advisable 
by  the  Executive  Committee  to  make  a  change,  and  after 
much  painstaking  labor  by  the  committee  appointed  for  the 
purpose,  the  present  quarters  for  our  library  and  meeting 
rooms  were  obtained  at  a  rental  of  $50  per  month,  which  in- 
cludes light  and  janitor  services.  Our  museum,  which  occu- 
pies a  large  floor  space,  with  the  kindly  consent  of  the  school 
authorities,  was  placed  in  the  North  Side  High  School  Build- 
ing, where  it  is  open  to  the  public  and  will,  in  addition,  serve 
as  a  stimulus  to  the  students  of  the  geological  classes  of  that 
school. 

The  assistant  secretary,  Miss  Riddle,  has  rendered  good 
and  efficient  service,  especially  to  the  secretary  and  treasurer, 
and  for  her  zeal  and  ever  loyal  interest  to  the  welfare  of  the 
Society  I  wish  to  express,  on  behalf  of  all  its  members,  our 
grateful  appreciation. 

DR.  WILLIAM  A.  JOHNSTON, 

Secretary. 


REPORT  OF  THE    TREASURER   OF  THE    COLORADO 

SCIENTIFIC  SOCIETY  FOR  THE  YEAR  ENDING 

DECEMBER  16TH,  1911. 

418  Boston  Building,  Denver,  Colo.,  Dec.  16th,  1911. 

RECEIPTS. 

Balance  from  statement  of  1910... $    351.11 

Annual  dues  - 1,805.00 

Rent  - 455.00 

Annual  dinner 189.00 

Sale  of  Proceedings 25.00 

Life  memberships 300.00 

Cancelled  fire  insurance 16.80 

Miscellaneous  ..  10.30 


$3,152.21     $3,152.21 
DISBURSEMENTS. 

Rent $1,100.00 

Printing  Proceedings 384165 

Printing  Notices,  Ballots  and  Stationery..  233.75 

Lighting 28.95 

Illustrating  lectures  41.70 

Postage  and  Envelopes 133.68 

Fire  insurance 86.20 

Salary  of  assistant  secretary 580.00 

Petty  cash 73.55 

Periodicals,  books  and  binding • 39.00 

Library  furnishings  and  repairs 29.70 

Exchange .75 

Annual  dinner 261.45 

Moving  to  present  quarters. 99.10 

Engraving  resolutions 6.00 

Miscellaneous   .  18.50 


$3,116.98     $3,116.98 
Cash  on  hand 35.23 

$3,152.21 


REPORT  OF  THE  TREASURER  yii 

This  report  shows  a  total  collection  of  $2,801.10  as  against 
$2,819.00  in  1910,  a  falling  off  of  $17.90.  The  total  disburse- 
ments as  shown,  were  $3,116.98  as  against  $2,861.53  for  1910, 
an  increase  of  $255.45. 

In  analyzing  and  comparing  the  expenditures  with  those 
of  the  previous  year,  you  will  find  the  comparison  as  follows : 

DECREASE. 

Rent  account $100.00 

Printing  of  Proceedings 80.55 

Periodicals,  books  and  binding 26.05 

Exchange   1.20 

Annual  dinner  24.35 

Miscellaneous  ..  51.00 


$283.15 
INCREASE. 

Printing  Notices,  Ballots,  Circulars,  etc.... $  90.05 

Lighting   6.20 

Postage  and  envelopes 10.80 

Insurance  17.40 

Salary  of  assistant  secretary 270.00 

Petty  cash  18.55 

Library  repairs  and  furnishings 12.80 

Illustrating  lectures  7.70 

Moving  99.10 

Engraving  resolutions 6.00 


$538.60 
$283.15 

$255.45 

The  chief  items  of  increase  fall  on  cost  of  printing  notices, 
ballots  and  stationery,  which  is  due  largely  to  the  extra  no- 
tices and  circulars  sent  out  in  connection  with  organizing  of 


Viii  REPORT  OF  THE  TREASURER 

the  "Sections."  The  other  two  important  items  are  the  in- 
crease in  the  salary  of  the  assistant  secretary,  and  the  cost  of 
moving.  Respectfully  submitted, 

J.  W.  RICHARDS, 

Attest :  Treasurer. 

RICHARD  A.  PARKER, 

Chairman.    J-  Auditing  Committee. 
FRANK  E.  SHEPARD. 

December  18th,  1911. 


PROCEEDINGS  OP  THE  COLORADO  SCIENTIFIC  SOCIETY. 
VOL.  X,  pp:  123-130. 


THE  WATER  SUPPLY  OF  COLORADO. 

By  CHARLES  W.  COMSTOCK. 


Address  of  the  Retiring  President  read  at  the  meeting  of  the  Society,  December  16,  1911. 


There  is  a  well  established  custom  among  societies  de- 
voted to  the  advancement  of  learning,  in  accordance  with  which 
the  retiring  presiding  officer  outlines  a  field  wherein  his  con- 
freres may  labor  with  advantage  for  the  discovery  of  prin- 
ciples and  the  accumulation  of  facts  which  are  needed  in  the 
work-a-day  world.  Thus,  while  the  papers  and  discussions  of 
the  year  are  contributions  toward  the  solution  of  problems 
previously  presented,  the  function  of  the  address  at  the  annual 
meeting  is  to  state  another  problem  which  has  been  forced  to 
the  front  amid  the  changing  conditions  and  which  demands 
our  attention. 

Conforming  to  this  custom,  which  I  think  an  admirable 
one,  I  have  chosen  to  discuss  a  subject  which  has  occupied 
most  of  my  attention  for  a  number  of  years  just  past,  viz.: 
"The  Water  Supply  of  Colorado." 

At  the  risk  of  being  thought  elementary,  I  must  revert  to 
first  principles  and  consider  the  source  of  all  water,  i.  e.,  pre- 
cipitation from  the  atmosphere.  Rain  or  snow  falls  and  im- 
mediately divides  itself  among  a  number  of  channels.  A  por- 
tion is  again  evaporated  directly  from  the  surface  of  the 
ground  or  from  the  snow  surface.  Another  portion  sinks  into 
the  ground,  is  absorbed  by  vegetation,  and  either  becomes  a 
part  of  the  plant  itself,  or  is  evaporated  from  its  foliage.  Still 
another  part  finds  its  way  into  the  ground  far  enough  to  be 
beyond  the  reach  of  atmospheric  influences  and  becomes  part 
of  the  great  body  of  ground  water.  This  third  portion  itself 


124         THE  WATER  SUPPLY  OF  COLORADO 

may  be  subdivided  into  two,  one  becoming  part  of  what  is 
ordinarily  known  as  "ground  water/'  and  the  other  joining  the 
deeper  subterranean  flow.  Finally,  a  fourth  portion  runs  off 
the  surface  of  the  ground  and  finds  its  way  into  the  channels 
of  surface  streams. 

All  of  this  water,  except  that  absorbed  by  vegetation,  or 
evaporated,  may  under  proper  conditions,  become  available  for 
use.  The  subterranean  flow  supplies  artesian  wells,  of  which 
there  are  many  in  Colorado,  particularly  in  the  San  Luis  Val- 
ley. 

The  ground  water  is  in  sufficient  quantity  in  some  parts 
of  the  state  to  irrigate  small  tracts  of  land.  The  surface  flow, 
although  probably  only  a  small  fraction  of  the  total  precipita- 
tion, is  relied  upon  to  supply  nearly  all  our  demands  for  domes- 
tic, agricultural  and  industrial  purposes. 

The  division  of  the  water  among  these  various  modes  of 
distribution  varies  widely  with  the  geology,  the  topography  and 
the  climate  of  the  region  in  which  the  water  flows,  as  well  as 
with  the  distribution  in  time  of  the  precipitation  itself. 

To  cite  extreme  cases :  In  the  heart  of  the  mountain  ranges 
where  there  is  little  soil,  where  the  rocks  are  bare  and  the 
slopes  steep,  where  the  altitude  is  high  and  the  rocks  generally 
of  a  crystalline  character,  nearly  all  the  water  which  falls 
divides  itself  into  two  classes — the  first,  covered  by  evapora- 
tion, and  the  last  covered  by  surface  run-off.  Although  tem- 
peratures are  generally  low  in  such  localities,  the  winds  blow 
almost  constantly,  frequently  with  great  violence,  and  the  ten- 
sion of  the  aqueous  vapor  in  the  atmosphere  is  very  low.  These 
two  conditions  do  more  to  increase  evaporation  than  a  high 
temperature.  Vegetation  is  scant  .or  entirely  absent,  and, 
therefore,  plays  no  part  in  the  distribution  of  the  water.  There 
is  little  or  no  soil,  and  the  rocks  are  crystalline  and  compact. 
Therefore,  the  quantity  absorbed  is  relatively  insignificant.  On 
the  other  hand,  the  slopes  are  steep  and  water  runs  very 
rapidly  to  the  natural  drainage  lines  of  the  country. 

Per  contra,  in  the  open  prairie,  such  as  forms  the  east- 
ern forty  per  cent,  of  this  state,  all  the  conditions  are  changed. 


COMSTOCK]  THE    WATER    SUPPLY    OF    COLORADO  125 

The  topographical  relief  is  small  and  the  slopes  are  slight. 
There  is  a  considerable  quantity  of  vegetation,  even  on  our 
most  barren  plains.  The  soil  and  sub-soil  are  deep  and  often 
very  porous.  Even  the  rocks  themselves  which  underlie  the 
soil,  or  which  outcrop  in  places,  are  sedimentary  and  capable  of 
absorbing  large  quantities  of  water.  The  temperatures  are 
higher,  but  the  winds,  as  a  rule,  less  constant,  and  the  tension 
of  aqueous  vapor  generally  greater. 

We  here  find  one  condition  which  makes  for  greater  evap- 
oration than  in  the  mountains,  and  two  which  tend  to  decrease 
it.  The  net  result  we  do  not  know.  The  water  falling  on  por- 
ous and  absorbent  soil  with  gradual  slopes  does  not  run  off 
readily,  but  is  absorbed  in  large  quantities.  The  precipitation 
itself  comes  mostly  in  the  form  of  rain  in  the  warmer  portions 
of  the  year,  whereas  in  the  mountains  it  is  chiefly  in  the  form 
of  snow  during  the  fall  and  winter  months.  The  vegetation 
directly  absorbs  some  water  and  facilitates  the  evaporation  of 
more. 

Thus  we  find  that  while  in  the  mountains  very  little  water 
is  absorbed  by  soil  or  rocks,  on  the  plains  a  great  deal  is  dis- 
posed of  in  this  way.  The  quantity  evaporated  on  the  plains, 
as  compared  with  the  mountains,  is  unknown,  but  is  known  to 
be  very  great,  and  some  is  absorbed  by  vegetation,  which  is 
not  the  case  at  extremely  high  altitudes. 

The  general  result  is  that  the  run-off  from  the  plains 
areas  to  the  channels  of  the  natural  streams  is  insignificant, 
except  on  those  rare  occasions  of  very  great  precipitation 
within  a  short  time.  This  distinction  is  so  marked  in  what  is 
known  as  the  "arid"  or  "semi-arid"  region  that  the  drainage 
area  of  a  stream  is  quite  commonly  divided  into  two  portions 
which  are  known  respectively  as  "contributing"  and  "non- 
contributing"  areas. 

To  be  enabled  to  make  the  best  use  of  the  water  which 
falls  to  our  lot,  we  should  know  with  accuracy  the  total  quan- 
tity supplied  and  the  proportion  of  it  which  is  disposed  of  in 
these  various  ways,  under  the  great  variety  of  conditions 
which  exist  in  the  state. 


126  THE    WATER    SUPPLY    OF    COLORADO 

Three  of  the  elements  mentioned  are  capable  of  direct 
measurement,  viz. : 

Precipitation ; 

Surface  run-off; 

Evaporation. 

Some  work  has  also  been  done  in  attempts  to  measure  the 
absorption  by  and  percolation  through  various  soils.  The  re- 
sults so  far,  however,  have  not  been  such  as  to  warrant  any 
generalizations. 

What  do  we  know  about  precipitation  in  Colorado  ? 

The  Monthly  Weather  Review,  for  September,  1911,  an 
official  publication  of  the  United  States  Weather  Bureau,  gives 
a  list  of  156  rainfall  stations  in  this  state.  Of  these,  forty-five 
are  in  the  Platte  River  drainage  basin ;  thirty-nine  in  the  Ar- 
kansas ;  two  in  the  water-shed  of  the  Cimarron ;  ten  in  the  Rio 
Grande  basin,  and  sixty-two  in  the  Colorado  River  drainage. 
This  totals  158,  but  two  of  these  stations  are  counted  twice; 
that  at  Corona  is  common  to  the  South  Platte  and  the  Colorado 
drainage,  while  that  at  Marshall  Pass  is  common  to  the  Ar- 
kansas and  the  Colorado. 

The  area  of  Colorado  is  103,948  square  miles.  We  thus 
have  on  the  average  one  rainfall  station  to  each  663  square 
miles,  or,  say,  one  to  an  area  of  twenty-six  miles  square.  This 
number  might  be  considered  adequate,  if  the  conditions  upon 
which  precipitation  depends  were  even  approximately  uniform 
throughout  the  state,  which,  however,  they  are  not. 

By  way  of  comparison,  we  may  note  the  distributions 
of  these  stations  in  some  other  parts  of  the  world. 

In  France  the  drainage  basin  of  the  Seine  is  30,327  square 
miles.  The  government  there  maintains  423  precipitation  sta- 
tions, or  one  to  each  seventy-two  square  miles.  This  is  as 
one  for  each  two  townships,  as  compared  with  one  for  each 
eighteen  townships  in  Colorado. 

In  the  valley  of  the  Rhone  there  is  a  precipitation  station 
for  each  ninety-six  square  miles ;  in  Switzerland,  one  for  each 
forty-four  square  miles. 


COMBTOCK]  THE    WATER    SUPPLY    OF    COLORADO  127 

The  entire  area  of  France  is  less  than  twice  that  of  Colo- 
rado, and  if  we  would  maintain  precipitation  records  compar- 
able with  those  abroad,  we  must  have  not  less  than  1,400  pre- 
cipitation stations  in  the  state  of  Colorado.  Even  the  very 
large  number  established  in  the  basin  of  the  Seine  is  deemed 
insufficient  by  the  engineers  charged  with  the  improvement 
and  maintenance  of  the  water-ways  in  that  region,  and  in  the 
most  elaborate  and  exhaustive  report  on  the  flood  of  January, 
1910,  prepared  by  the  government  engineers  and  recently  is- 
sued by  authority  of  the  French  government,  a  substantial  in- 
crease in  the  number  of  these  stations  is  proposed. 

At  the  present  time,  the  practice  in  Colorado  among  those 
who  are  not  trained  to  scientific  modes  of  thought,  is  to  apply 
the  records  of  the  nearest  station  to  whatever  area  may  be 
under  consideration,  whether  it  be  large  or  small,  thus  uncon- 
sciously assuming  a  uniformity  in  the  distribution  of  rainfall 
which  the  most  casual  observer  knows  does  not  exist. 

The  question  is  frequently  asked:  What  is  the  ratio  of 
run-off  to  rainfall  in  this  or  that  drainage  area  ?  This  question 
is  not  answerable  for  any  drainage  area  in  the  state  of  Colo- 
rado, for  the  obvious  reason  that  we  do  not  know  how  much 
water  falls  in  any  such  drainage  area. 

Meagre  and  unsatisfactory  as  our  run-off  records  may  be, 
we  know  more  about  the  total  run-off  than  we  do  about  the  total 
precipitation. 

A  second  element  directly  measurable  is  the  run-off,  and 
on  this  more  money  has  been  spent  and  more  work  done  than 
on  any  other,  although  the  records  and  results  are  far  from 
satisfactory,  partly  because  some  of  the  work  has  been  poorly 
done,  but  chiefly  because  of  lack  of  continuity. 

Not  counting  stations  maintained  by  private  parties,  the 
records  of  which  are  not  accessible  to  the  public,  there  are 
now  seventy-three  stream  gauging  stations  in  Colorado.  Of 
these,  eighteen  are  located  in  the  Platte  water  shed,  twelve  in 
the  Arkansas,  nine  in  the  Rio  Grande,  and  thirty-four  in  the 
drainage  area  of  the  Colorado.  This  last,  of  course,  includes 


128  THE    WATER    SUPPLY    OF    COLORADO 

more  than  one-third  of  all  the  state,  being  the  entire  area  west 
of  the  main  range  except  that  tributary  to  the  Rio  Grande. 

This  number,  small  as  it  is,  is  five  times  as  great  as  it  was 
three  years  ago.  It  means  an  average  of  one  stream  gauging 
station  for  each  1,424  square  miles  in  the  state. 

In  the  basin  of  the  Seine  the  French  government  main- 
tains 120  stream  gauging  stations,  or  one  for  each  253  square 
miles. 

Concerning  this  phase  of  the  water  supply  question,  there 
is  little  to  be  said  except  that  there  is  need  for  greatly  ex- 
tending it,  and  strenuous  efforts  must  be  made  to  avoid  any 
break  in  the  continuity  of  the  records. 

In  the  matter  of  evaporation  measurements,  almost  noth- 
ing has  been  done.  Observations  have  been  desultory  and  scat- 
tered. Diligent  search  has  failed  to  reveal  more  than  one  rec- 
ord extending  through  an  entire  year.  Such  observations  as 
have  been  made  have  been  made  without  uniformity  of  method 
or  procedure  and  are  hardly  comparable. 

So  far  from  being  able  to  know  the  comparative  evapora- 
tion in  the  mountains  and  on  the  plains,  we  are  not  even  in 
position  to  state  with  definiteness  the  average  annual  evap- 
oration at  any  one  place  in  Colorado.  This  is  without  doubt  a 
task  which  should  be  undertaken  by  the  State  Hydrographic 
Service,  but  it  is  a  formidable  one  for  several  reasons. 

Evaporation  stations  depend  for  their  value  upon  measure- 
ments which  must  be  made  with  great  precision  and  at  fre- 
quent intervals.  This  means  the  expenditure  of  a  considerable 
sum  for  the  equipment  of  each  station,  and  the  attendance  of  a 
skilled  observer.  The  work  cannot  be  entrusted  to  such  observ- 
ers as  happen  to  be  resident  near  the  station,  as  is  done  with  a 
fair  degree  of  satisfaction  with  stream  gauging  stations.  Our 
legislature  should  be  asked  to  provide  for  an  equipment  of  this 
kind,  and  for  the  proper  conduct  of  these  observations. 

With  accurate  knowledge  of  the  total  precipitation,  the 
total  run-off,  'and  the  total  evaporation,  we  can  ascertain  by 
difference  the  quantity  of  water  absorbed  by  the  soil  and  the 


COMSTOCK]  THE    WATER    SUPPLY    OF    COLORADO  129 

vegetation.  No  method  is  apparent  by  which  any  direct  meas- 
urement of  this  quantity  can  be  made. 

Valuable  work  in  the  direction  of  the  measurement  of 
ground  water  flow  has  been  done  during  the  past  ten  years 
by  a  number  of  engineers  following  in  the  footsteps  of  Prof. 
Charles  S.  Slichter.  It  is  not  unlikely  that  this  may  lead  sooner 
or  later  to  some  method  by  which  we  can  determine  directly  the 
quantity  of  water  absorbed  by  the  soil  and  its  ultimate  disposi- 
tion. Along  this  line,  I  have  nothing  to  suggest. 

As  said  in  my  opening  paragraph,  I  have  only  attempted 
to  state  some  problems  demanding  solution.  The  demand  is 
real,  and  the  necessity  for  definite  answers  to  some  of  these 
questions  is  very  great.  For  these  reasons,  it  has  seemed 
proper  and  appropriate  that  they  be  called  to  the  attention  of 
The  Colorado  Scientific  Society. 


